A joint statement by the US-South Korean Nuclear Consultative Group also reaffirmed that any nuclear attack by Pyongyang on South Korea "will be met with a swift, overwhelming, and decisive response."

"The United States reaffirmed its unwavering commitment to provide extended deterrence to the ROK (Republic of Korea) backed by the full range of US capabilities including nuclear," said the statement published by the White House.

US President Joe Biden had issued a similar, strongly worded warning in April, saying that any nuclear attack by North Korea would "result in the end" of the Pyongyang government.

And five months earlier, US Defense Secretary Lloyd Austin warned that any nuclear attack by the North against the US or its allies would mean the "end of the Kim regime."

North Korea last year declared itself an "irreversible" nuclear power and has repeatedly said it will never give up its nuclear program, which the regime views as essential for its survival.

And last month Pyongyang successfully put a military spy satellite into orbit. It has since claimed its eye in the sky was already providing images of major US and South Korean military sites.